Electromagnetic relays



Dec. 1, 1959 A. J. LEWUS ELECTROMAGNETIC RELAYS Filed Sept. 20, 1954 IN V EN TOR. A/exander' J Lewus "Mn, mm, M

United States Patent ELECTROMAGNETIC RELAYS Alexander J. Lewus, Cicero, Ill. Application September 20, 1954, Serial No. 457,190

9 Claims. (01. 317-176) vide an electromagnetic relay of the current-responsive.

or marginal type that embodies an improved and simplified arrangement for adjusting the magnetic reluctance of the magnetic circuit thereof so as to accommodate ready adjustment of the characteristics of the relay to match the characteristics of a wide range of induction motors of the split-phase or capacitor type.

.Another object. of the invention is to provide in an electromagnetic relay of the type noted, an improved arrangement for preventing chatter of the armature with respect to the cooperating pole piece when the associated winding is energized with an alternating current. A further object of the invention is to provide in an electromagnetic relay of the type noted, an improved arrangement for preventing sticking of the armature to the cooperating pole piece as a result of residual magnetism 'therebetween when the alternating current traversing the associated winding is reduced to a value at whichgrestorationof the armature is desired.

' Further features of the invention pertain to the particular-arrangernent of the elements of the electromagnetic relay, whereby the above-outlined and additional operatingfeatures thereof are attained.

"The invention ,.both as to its organization andmethod of operation, together with further objects and advantages thereof, will 'best be understood by reference to the following specification, taken in connection with the accompanying drawing, in which:

Figurel is a vertical sectional view of an electromagnetic relay embodying the present invention;

Fig.2 is a fragmentary side view of the relay shown in Fig. 1, illustrating the central portion thereof with thewinding removed;

Fig, 3 is a vertical sectional view of a modified form of the electromagnetic relay embodying the present invention; f i t t Fig.4 is.,a fragmentary side view of the relay shown in Fig. 3, illustrating the central portion thereof with the winding removed;

Fig. 5-is a 'vertical sectional view of another modified form of the electromagnetic relay embodying the present invention; I

1 Fig." 6 is a fragmentaryside view of the relay shown in Fig. 5, illustrating the central portion thereof with the winding removed;

t Fig. 7 is a fragmentary vertical sectional view of a further modified form of the electromagnetic relay emb'odying ,the present invention; and

Fig. 8 is afragrnent'ary plan view of the relay shown in Fig; 7.

Referring to Figs. 1 and 2 of the drawing, the electromagnetic relay 10 there illustrated and embodying the features of the present invention comprises a supporting base 11 formed of insulating material, such, for example, as Bakelite," and a substantially Z-shaped field element 12 formed of magnetic material and provided with a body 13 terminating in two oppositely directed arms 14 and 15. In the arrangement, the arm 14 extends forwardly with respect to the adjacent lower end of the body 13, and the arm 15 extends rearwardly with respect to the adjacent upper end of the body 13. The arm 14 is suitably secured to the adjacent upper surface of the supporting plate 11 by an arrangement including a pair of rivet eyelets 16 extending through aligned openings respectively provided in the plate 11 and in the arm 14. Also, a tubular member 17 formed of magnetic material is carried by the adjacent upper surface of the arm 14 and secured in place by the eyelets 16 extending through aligned openings provided therein. The member 17 comprises an upstanding substantially cylindrical barrel 18 disposed forwardly with respect to the body 13 of the field element 12, and a pair of lower oppositely directed flanges 19 that are directly secured to the adjacent upper surface of the arm 14 as previously noted. Preferably, the barrel 18 has a longitudinally extending slit 20 formed therein in order to interrupt the electrical circuit path therearound' so as to minimize eddy currents inthe member 17 that are induced therein when the winding provided on the associated winding spool is- Also the relay energized with an alternating current. 10 comprises a unitary winding spool and supported winding that is removably carried by the member 17, the heads of the winding spool being indicated at 21 and 22, and the winding being indicated at 23. The heads 21 and 22 of the winding spool are formed of insulating material, such, for example, as Bakelite, and the composite winding 23 is formed of suitable conducting wire, such, for example, as copper, or the like, individual terminals of the composite winding 23, not shown, being suitable insulated from each other.

Also, the relay 10 comprises an armature 24 having a substantially Z-shape and including a body 25 terminating in two oppositely directed arms 26 and 27. The arm 26 projects forwardly with respect to the associated upper end of the body 25 and cooperates with the adjacent outer end of the barrel 18, while the arm 27 projects rearwardly from the associated lower end of the body 25 and constituting a work lever. The armature 24 is formed of magnetic material and is pivotally mounted upon the upper portion of the body 13 of the field element 12 somewhat above the upper end of the barrel 18 and intermediate the arms 14 and 15 of the field element 12. Specifically, a substantially centrally disposed opening 28 is formed in the upper portion of the field element 12 at the junction between the upper end of the body 13 and the arm 15, whereby two laterally spaced-apart sides 19 extend between the upper end of the body 13 and the rear extremity of the arm 15. Further, two laterally spaced-apart side notches 30 are provided in the sides 29 that respectively receive two laterally spaced-apart tabs, not shown, provided on the opposite sides of the armature 24 adjacent to the junction between the body 25 and the arm 26 thereof. Thus it will be understood that the arrangement comprising thetoward and away from'the pole end of the barrel 18' about the tabs, not shown, riding in the side notches 39.

Patented Dec. 1, 1959 The armature 24 is normally biased in its released position illustrated by an arrangement comprising a tension element or spring 31 projecting through the opening 28 and cooperating between the front end of the arm 26 and a screw 32. More particularly, a substantially centrally disposed notch 33 is provided in the front end of the arm 26 that receives the front end of the spring 31, the front end of the spring being arranged in the notch 33 and hooked over the lower surface of the outer end of the arm 26. The rear end of the arm 15 is curved both rearwardly and downwardly and terminates in a tab 34 having an opening therein in which the screw 32 is located, the front end of the screw 32 having a hole therein that receives the rear end of the spring 31, and the rear end of the screw 32 carrying an associated adjusting nut 35. As described above, the front end of the tension element 31 is pivotally connected to the front end of the arm 26 in the notch 33, while the rear end of the tension element 31 is connected to the screw 32; whereby it will be understood that when the nut 35 is rotated, the screw 32 is moved in the associated opening provided in the tab 34 so that the position of the front end of the screw 32 is adjusted both in the horizontal and vertical directions effecting corresponding movements of the rear end of the tension element 31. Accordingly, the tension element 31 normally biases the armature 24 in the counterclockwise direction about its pivotal mounting; and the moment of this bias exerted by the tension element '31 upon the front end of the arm 26 may be selectively varied or adjusted depending upon the position of the screw 32 in the associated opening provided in the tab 34. The moment of the bias is adjusted, both by the variation of the tension in the spring 31 and by the variation in the elevation of the front end of the screw 32 with respect to the front end of the arm 26.

Further, the relay comprises a stationary switch spring 36 and a movable switch spring 37, both suitably mounted upon the plate 11 and insulated from each other. The switch springs 36 and 37 are formed of suitable electrical conducting material, and the switch spring 37 possesses considerable resiliency. The switch springs 36 and 37 respectively carry stationary and movable contacts 38 and 39 that may be formed of precious metal for the purpose of making and breaking the electrical circuit between the switch springs 36 and 37. Also, the movable switch spring 37 carries a pair of laterally spaced-apart upstanding arms 40 carrying a laterally extending pin 41 therebetween upon which an insulating roller 42 is mounted. The roller 42 may be formed of glass, porcelain, or the like, and is readily rotatable upon the pin 41 in order to eliminate friction therebetween. The outer surface of the roller 42 is urged by the resiliency of the movable switch spring 37 into engagement with the adjacent lower surface of the work lever 27 of the armature 24. When the armature 24 occupies its normal released position illustrated, the work lever 27 engaging the outer surface of the roller 42 retains the movable switch spring 37 in its lower position so that the contacts 38 and 39 are disengaged. When the armature 24 is moved into its attracted position with respect to the pole end of the barrel 18, it being pivoted in the clockwise direction, as illustrated in Fig. 1, the work lever 27 is' effectively moved away from the pin 41 so that the outer surface of the roller 42 rolls upon the adjacent surface of the work lever 27 as the roller 42 follows the work lever 27 due to the resiliency of the movable switch. spring 37, whereby the contact 39'is moved into engagement with the contact 38, closing the electric cir-- cuit between the switch springs 36 and 37. When the armature 26 is moved into its fully attracted position, the work lever 27 disengages the adjacent surface of the roller 42. so as positively to prevent chatter of the contacts 38 and 39. Substantially when the armature 24 is returned to its normal released position, as illustrated in Fig. 1, the work lever 27 engaging the adjacent surface of the roller 42 forces the roller 42, as well as the pin 41 and the movable switch spring 37, downwardly so that the outer surface of the roller 42 rolling upon the adjacent lower surface of the work lever 27 moves the movable switch spring 37 in order to disengage the movable contact 39 from the stationary contact 38 so as again to interrupt the electric circuit between the switch springs 36 and 37.

Further, aligned openings 43 and 44 are respectively formed in the plate 11 and in the arm 14, the openings 43 and 44 being arranged in alignment with the inner end of the barrel 18, and the opening 44 being threaded and engaging a threaded exterior surface provided on the inner end of a core element 45 projecting through the openings 43 and 44 and arranged within the barrel 18. The core element 45 is formed of magnetic material and the outer end thereof comprises a pole end terminating adjacent to the outer end of the barrel 18. The intermediate and outer end of the core element 45 is of reduced cross-sectional area and carries a surrounding shading coil 46 formed of copper or other conducting material for the purpose of producing a phase-shift between the magnetic fluxes respectively traversing the barrel 18 and the core element 45 so as to prevent chatter of the armature 24 when the winding 23 is energized with an alternating current. The shading coil 46 is of elongated annular form and the outer end thereof may be disposed substantially flush with the outer or pole end of the core element 45; and it will be understood that the pole end of the core element 45 may be adjusted with respect to the adjacent po'le end of the barrel 18 and consequently toward and away from the arm 26 of the armature 24 to accommodate longitudinal adjustment of the gap provided between the pole end of the core element 45 and the arm 26 by virtue of the arrangement of the engaging threads provided in the opening 44 and upon the outer surface of the inner end of the core element 45, thereby to adjust the effective magnetic reluctance of the composite core of the relay 10. The extreme inner end of the core element 45 has a slot 47 formed therein that is adapted to receive a screw driver, or the like, to facilitate the adjustment noted; and the inner end of the core element 45 also carries a lock nut 48 so that the adjusted position thereof within the barrel 18'may be retained by virtue of the cooperation between the lock nut 48 and the adjacent lower surface of the plate 11.

Since the shading coil 46 is carried directly by the core element 45, it is movable therewith in the previously described adjustments; and it will be understood that the shading coil 46 produces the previously-mentioned phaseshift between the magnetic fluxes respectively traversing the core element 45 and the barrel 18 by virtue of the circumstance that the shading coil 46 surrounds only the core element 45, and is, in turn, surrounded by the barrel 18. More specifically, both the build-up and the decay of the magnetic flux in the core element 45 are retarded by the circulating currents induced in the shading coil 46; whereas both the build-up and the decay of the mag-' netic flux in the barrel 18 are free to follow directly the magnetomotive force of the winding 23. It is an important feature of the arrangement that the adjustment of the longitudinal position of the core element 45 correspondingly adjusts the magnetic flux traversing the movable core element 45 with respect to the magnetic flux traversing the stationary barrel 18, whereby the adjustment of the core element 45 also effects adjustment of the previously mentioned phase-shift between the.

magnetic fluxes respectively traversing the core element 45 and the barrel 18 so that a wide range of marginal action of the relay 10 may be readily obtained.

Referring now to Figs. 3 and 4, the modified form of the relay there illustrated, and embodying the features of the present invention, is fundamentally of the same construction as the relay 10, described above, ex-

cept that the corresponding core element is .of substantially uniform cross-sectional area and the corresponding shading coil 146 surrounds the core element 145 from end-to-end; whereby, in fact, it is the inner end of the shading coil 146 that is provided with the threads that cooperate with the threaded opening 144 provided in the arm 114 of the field element 112 in order to accommodate the longitudinal adjustment of the core element 145 and the shading coil 146 as a unit, in the manner and for the purpose previously explained.

In this form of the relay 110, the core element 145 may be formed of a solid piece of magnetic material or of a compressed mass of magnetic powder or granules, the magnetic material comprising various metallic elements or compounds or alloys thereof.

Referring now to Figs. 5 and 6, the modified form of the relay 210 there illustrated, and embodying the features of the present invention, is fundamentally of the same construction as the relay described above, except that the corresponding core element 245 is of substantially uniform cross-sectional area and the corresponding shading coil 246 is carried by the barrel 218, whereby the shading coil 246 is stationary and does not partake of the longitudinal adjustments of the core element 245. In the arrangement, the tubular shading coil 246 may be staked in place within the tubular barrel 218 by an arrangement including an annular groove 218a provided in the tubular barrel 218, whereby the tubular shading coil 246 serves to guide the longitudinal movements of the core element 245 in the manner and for the purpose previously explained.

Referring now to Figs. 7 and 8, the modified form of the relay 310 there illustrated, and embodying the features of the present invention, may be identical to any one of the relays 10, 110 or 210, except that a nonmagnetic shim 350 is arranged between the flanges 319 carried by the tubular barrel 318 and the adjacent surface of the arm 314 of the field element, the shim 350 being secured in place by the eyelets 316 extending through holes provided therein. This arrangement introduces an additional gap into the magnetic circuit so as to reduce the residual magnetism therein in order to prevent sticking of the associated armature with respect to the cooperating core.

The relays 10, 110, 210 and 310 are particularly wellsuited for use in the control circuits of a wide variety of induction motors, wherein the magnetic circuits of the relays are saturated during start conditions and unsaturated during run conditions of the motors. Moreover, the adjustments of the operating characteristics of the relays, as previously described, accommodate ready matching thereof with respect to a wide range of operating characteristics of the induction motors.

In view of the foregoing, it is apparent that there has been provided an electromagnetic relay incorporating improved structure for varying the current responsive or marginal characteristics thereof over a wide range, thereby lending flexibility to the relay for use in the control circuits of a great variety of induction motors.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An electromagnetic relay comprising a magnetic field element, a longitudinally extending tubular magnetic member secured at its inner end to said field element, a longitudinally extending winding carried by said tubular member in surrounding relation therewith and adapted to be energized with an alternating current, a magnetic armature, a pivotal connection between said armature and said field element, said armature having a free end cooperating with the outer end of said tubular member and movable toward and away from the same, means biasing the free end of said armature away from the outer end of said tubular member, said field element having an opening formed therein in longitudinal alignment with said tubular member and communicating with the inner end thereof, a longitudinally extending substantially rod-like magnetic core element carried by said field element within said opening and projecting longitudinally into said tubular member and having an outer pole end disposed adjacent to the outer end of said tubular member and also cooperating with the free end of said armature and normally separated therefrom by a gap, means for selectively adjusting the longitudinal position of said core element in said tubular member so as selectively to adjust the length of the gap between the pole end of said core element and the free end of said armature, said core element being spaced radially inwardly with respect to said tubular member to provide an elongated and substantially annular space therebetween, and a longitudinally extending tubular shading coil disposed within said tubular member and surrounding said core element and substantially completely filling the elongated annular space therebetween in order to produce a phase-shift between the magnetic fluxes respectively traversing said tubular member and said core element when said winding is energized so as to prevent chatter of said armature.

2. The electromagnetic relay set forth in claim 1, wherein said tubular member is split longitudinally in order to prevent the circulation of eddy currents therearound.

3. The electromagnetic relay set forth in claim 1, wherein said adjusting means comprises cooperating threads respectively carried by said field element within said opening and by the inner end of said core element.

4. The electromagnetic relay set forth in claim 1, wherein said shading coil is secured to said tubular member, and said core element is movable longitudinally both in said tubular member and in said shading coil.

5. The electromagnetic relay set forth in claim 1, and further comprising a non-magnetic shim arranged be tween said field element and the inner end of said tubular member.

6. The electromagnetic relay set forth in claim 1, wherein said shading coil is secured to said core element and is movable longitudinally therewith in said tubular member.

7. The electromagnetic relay set forth in claim 6, and further comprising a non-magnetic shim arranged between said field element and the inner end of said tubular member.

8. An electromagnetic relay comprising a magnetic field element, a longitudinally extending tubular magnetic member secured at its inner end to said field element, a longitudinally extending winding carried by said tubular member in surrounding relation therewith and adapted to be energized with an alternating current, a magnetic armature, a pivotal connection between said armature and said field element, said armature having a free end cooperating with the outer end of said tubular member and movable toward and away from the same, means biasing the free end of said armature away from the outer end of said tubular member, said field element having an opening formed therein in longitudinal alignment with said tubular member and communicating with the inner end thereof, a longitudinally extending substantially rod-like magnetic core element carried by said field element within said opening and projecting longitudinally into said tubular member and having an outer pole end disposed adjacent to the outer end of said tubular member and also cooperating with the free end of said armature and normally separated therefrom by a gap, said core element being spaced radially inwardly with respect to said tubular member to provide an elongated and substantially annular space therebetween, a longitudinally extending tubular shading coil also disposed within said opening and projecting longitudinally into said tubular member and surrounding said core element and substantially completely filling the elongated annular space therebetween and secured to said core element, said shading coil producing a phase-shift between the magnetic fluxes respectively traversing said tubular member and said core element when said winding is energized so as to prevent chatter of said armature, and means for selectively adjusting the longitudinal position of said core element and said shading coil as a unit in said tubular member so as selectively to adjust the length of the gap between the pole end of said core element and the free end of said armature.

9. The electromagnetic relay set forth in claim 8,,

wherein said adjusting means comprises cooperating threads respectively carried by said field element within said opening and by the inner end of said shading coil.

References Cited in the file of this patent UNITED STATES PATENTS 

